Before the barbecues are stored for the winter, consider this alternative if you aren't eating only fiber, protein, and healthy fat. These are fantastic.
Make a marinade of 1/2 cup olive oil, 1 Tbsp chopped fresh rosemary, 1 Tbsp finely chopped shallot, 1/2 tsp kosher salt, and 1/4 tsp freshly ground pepper in a large Ziplock bag.
Halve and seed the peppers, then flatten them. Cut the squash lengthwise in 1/2 inch thick slices. Slice the tomato 1/2 inch thick. Remove the stems from the portobello.
Place all of the vegetables into the marinade turning occasionally for at least 15 minutes.
Grill over medium heat turning once. The mushrooms will take 12 to 14 minutes, the squash 8 to 10 minutes, the peppers 6 to 8 minutes, and the tomato 3 to 4 minutes.
Grill the buns. Spread goat cheese on the bun.
Drizzle 3 Tbsp balsamic vinegar over all of the vegetables after removing them from the grill. Salt and pepper to taste.
Build sandwiches in layers with fresh basil between each layer.